In the field of data processing, the use of point of sale (POS) terminals has required and also has enabled rapid and accurate transfer of information from one location to another in a business operation. In the case of department stores, the sales data must be transmitted or communicated from one or more terminals throughout the store to a central computer or processing unit.
A filing system is used to provide and maintain inventory and price data on the huge number of items that are sold in the store. The filing system and the control therefor provide means for retrieving and updating data and information regarding the constantly changing inventory and prices for the overall operation.
Representative documentation in the field of file control systems includes Japanese Patent Spec. No. 209642/87 which discloses point of sale data files provided in a master terminal and in a backup master terminal and wherein both terminals update the data files in response to a request from a satellite terminal and transmit PLU (price look up) data to the satellite terminals.
U.S. Pat. No. 4,319,326, issued to Y. Uchida on Mar. 9, 1982, discloses a plurality of electronic cash registers and a consolidator unit which includes means for storing data corresponding to data for each operator of the registers.
U.S. Pat. No. 4,468,750, issued to M. E. Chamoff et al. on Aug. 28, 1984, discloses a system of smart terminals and a dumb controller coupled by means of a communications link. Each of the terminals has a programmable digital processor, entry devices and display devices.
U.S. Pat. No. 4,502,120, issued to S. Ohnishi et al. on Feb. 26, 1985, discloses a system for data transmission between slave cash registers and a master register wherein a transmitting device divides the data into parts and the capacity of a receiving device is identical with the capacity of a memory device.
U.S. Pat. No. 4,528,643, issued to C. C. Freeny on Jul. 9, 1985, discloses a system for reproducing information in material objects such as tapes, recordings, games, motion pictures, etc. at point of sale locations from a remote location in response to receiving an owner authorization code from the owner of the information.
U.S. Pat. No. 4,594,664, issued to K. Hashimoto on Jun. 10, 1986, discloses a master cash processing unit and a plurality of slave units wherein the aggregated sales data is identified by codes associated with each lot of data and is sent to the master unit.
U.S. Pat. No. 4,623,964, issued to M. E. Getz et al. on Nov. 18, 1986, discloses a homogeneous hierarchical computer business system wherein terminals have switches to couple them to one of two alternate bus structures, ideally to two different controllers, and the controllers maintain files dedicated to attached terminals.
And, U.S. Pat. No. 4,683,536, issued to M. Yamamoto on Jul. 28, 1987, discloses a plurality of credit terminals and one of such terminals collects sales data from other terminals and transmits such data to the host computer.
In a conventional point of sale system, a master file contained therein has to perform numerous operations such as control of communications with a satellite terminal, data collection, counting operations, issuance of reports and like operations. Additionally, the master file may have to provide registration of sold goods similar to operations performed by the satellite terminal so that with such additional operation the master file cannot respond in rapid manner to a request from the satellite terminal. Further, it is known that peripheral devices such as a keyboard, a display, a printer, or a bar code reader may fail and thus add to the load imposed on the master file or the problems associated therewith.
Still further, it is known that when one or more of the peripheral devices, which are not directly related or associated with the file controller, fail in operation or something goes wrong in the operation, the master file needs to be slaved down in order to solve the problem. If the system includes a backup master file, more burdens are imposed on the backup file and the system cannot respond to requests from satellite terminals in rapid manner. Since the data file of a backup master file needs to be updated in accordance with the transmission of data from a satellite terminal, more burdens are also imposed on the satellite terminal.